Patent Document 1 describes an electronic device such as a mobile phone that delivers an air conduction sound and a bone conduction sound to a user. Patent Document 1 also describes that the air conduction sound is a sound transmitted to the auditory nerve of the user when vibrated air caused by vibration of an object is transmitted to the ear drum via the ear canal and the ear drum vibrates. Patent Document 1 further describes that the bone conduction sound is a sound transmitted to the auditory nerve of the user via a part of the body of the user (the cartilage of the ear, for example) who is touching an vibrating object.
Patent Document 1 describes that a vibrator in the shape of a short rectangular plate formed of a piezoelectric bimorph and a flexible material is attached to an outer surface of the housing of the phone via an elastic member. Patent Document 1 also describes that, upon application of a voltage on the piezoelectric bimorph of the vibrator, a piezoelectric material stretches in a longitudinal direction causing bending vibration of the vibrator and, when the user makes the vibrator contact the auricle, the air conduction sound and the bone conduction sound are transmitted to the user.